sed

Created lørdag 22 oktober 2016

sed is a tool for manipulation text.

Spacing

# Double spaces (doesn't make double blank lines)
$ sed '/^$/d;G'

# Undo double spacing
$ sed 'n;d'

# Insert blank line above lines matching example
$ sed '/example/{x;p;x;}'

# Insert blank line below lines matching example
$ sed $'s/regexp/\\\n/wqg'

# Insert blank line below and above lines matching example
$ sed '/example/{x;p;x;G;}'

# Add a blank line after every 5 lines
$ sed 'n;n;n;n;G;'

Line numbering

# Line number for each line
$ sed = filename | sed 'N;s/\n/\t/'

# Only if the line is not empty
$ sed '/./=' filename | sed '/./N; s/\n/ /'

Whitespaces

# Remove whitespaces from beginning of each line
$ sed 's/^[ \t]*//'

# Remove whitespaces from end of each line
$ sed 's/[ \t]*$//'

# Remove whitespace from beginning and end of each line
$ sed 's/^[ \t]*;s/[ \t]*$'

Find and Replace

# Find and replaces all instances of foo and replaces it with bar
$ sed 's/foo/bar/g'

Reverse

# Re-arrange the lines (bottom to top)
$ sed '1!G;h;$!d'

# Reverse each character
$ sed '/\n/!G;s/\(.\)\(.*\n\)/&\2\1/;D;s/.'

Selective Printing

# Print out first line of a file
$ sed q

# Print out first 10 lines of a file
$ sed 10q

# Print out last 10 lines of a file
$ sed -e :a -e '$q;N;11,$D;ba'

# Print out lines witch contains example
$ sed -n '/example/p'

# Print out lines that does NOT contain example
$ sed -n '/example/!p'

# Print out line 8 to 12
$ sed -n '8,12p'

# Print out line 52
$ sed -n '52p'

Deleting

# Delete all duplicate lines (consecutive duplicates)
$ sed '$!N; /^\(.*\)\n\1$/!P; D'

# Delete the first 10 lines
$ sed '1,10d'

# Delete the last line
$ sed '$d'

# Delete every 8th line
$ sed 'n;n;n;n;n;n;n;d;'

# Delete lines containing example
$ sed '/example/d'

# Delete all blank lines
$ sed '/^$/d'